Alternating Current (“AC”) power inverters are gaining popularity as on-vehicle power sources for passenger cars/trucks, recreational vehicles, and heavy-duty long-haul trucks. Typically, these AC power inverters are designed to receive power from a low voltage Direct Current (“DC”) source such as a 12 V or 24 V battery. These AC power inverters typically have a low voltage set-point that allow the AC power inverters to run until the batteries supplying them are nearly completely drained.
In passenger cars and trucks, the AC power inverters are typically used while the vehicle is running. Because the alternator generates sufficient power, the AC power inverter is prevented from otherwise draining the vehicle's battery.
In recreational vehicles, the AC power inverters are usually paired with dedicated deep-cycle batteries that are charged from the vehicle's electrical system, from an AC powered charger, or from solar panels. Because these batteries are separate from, and isolated from, the batteries that are used to start the vehicle, the AC power inverter does not discharge the vehicle's starting batteries. Therefore, the AC power inverter can utilize the deep-cycle batteries until they are depleted without affecting the ability of the vehicle to start.
In contrast, on heavy-duty long-haul trucks, the AC power inverters are typically powered from the truck's batteries, which also serve to start the truck. Because the AC power inverters can be used for periods of time when the truck is not running, the AC power inverters often deplete the batteries to the point where they do not have sufficient energy to crank the engine and start the truck. Due to this problem, some equipment owners or managers do not allow their drivers to use AC power inverters in their trucks, or only allow drivers to use AC power inverters while the truck is running. Drivers who essentially live out of the trucks they drive want, and in some cases need, some of the comforts and offerings that AC power inverters provide.
In an attempt to solve this problem, inverters with higher low-voltage set-points have been used to preserve power for starting the engine. These have been somewhat successful, but in order to guarantee that the crank battery will have sufficient energy, the set-point must be set quite high. This causes problems with the AC power inverter turning off too soon when the driver/operator utilizes higher-power AC devices that draw a high current for a short period of time.
In another attempt to solve this problem, timers have been utilized in conjunction with AC power inverters that allow the inverter to be used for a predetermined number of hours. Again, these have been somewhat successful, but suffer from the problems of sometimes (when high-power AC devices are used) allowing too much energy to be used and thereby compromising the vehicle's ability to start. Another drawback is that the timer sometimes prohibits the drivers from being able to use devices that only require a small amount of energy, despite the batteries having sufficient energy to do so. The present invention seeks to solve these, and other, problems.